Re: ADA.STRINGS.INDEX_ERROR : a-strunb.adb:782

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 15/01/2018 13:00, Mehdi Saada wrote:

>> When deleting elements of a list by position the loop must run positions
>> in reverse:
>> [...]
>> That will keep the positions straight. Position /= index, BTW.
>> However, deleting characters from a string almost never has sense. You
>> probably should reconsider the algorithm.
> 
> Ah ? Why so ?

An empiric fact.

> And how come position =/ index ? "IND" is the same, isn't ?

Index can start at any number and for a user-defined string type it 
might be any discrete type, e.g. not a number.

When you use 1..X'Length that is position, When you use X'Range or 
X'First..X'Last that is index.

You cannot delete the element at an index, that would make the array 
non-contiguous. You can do it at a position, which makes indices of the 
elements slide.

Note that in Ada X'Length is of universal integer for all arrays. It is 
silently converted to Integer which gives a false impression of being an 
"index".

P.S. Unbounded and fixed-length strings are not properly designed due to 
language limitations, so Length (X) has the result of a wrong type.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de